Remote control system



May 22, 1945. R. HULTIN 2,376,359

REMOTE CONTROL SYSTEM Filed June 30, 1942 nu llllllI Will I INVENTOR.firm! flu ZZZ/z M %/m&

Patented May 22, 1945 REMOTE CONTROL srs'rmu Rune Hultin, Lldingo,Sweden, assignor to Aga- Baltic Aktiebolag, Stockholm, Sweden, acorporation of Sweden Application June so, 1942, Serial No. 449,202 InSweden March 5, 1942 4 Claims.

My invention relates to pressure operated remote control systems.

Pressure operated remote control systems have the advantage that largeamounts of power may be obtained by using a source of power (gasaccumulator or the like) which occupies a rather small space and is easyto transport. Therefore they are specially suitable for such mobilepurposes as military control systems, forinstance for orienting guns,search-lights and the like, although they are also useful in connectionwith stationary objects which are to be controlled remotely. Previoussystems of this type did no: effect suflicient control precision andfurthermore they were usually too complicated and consequently subjectto errors of various kinds. The use of such systems was thus limited tocases where only low precision was required and where reliability wasnot essential.

The present invention relates to a pneumatic remote control system whichoperates with high precision and which is simple and reliable. In thearrangement according to the present invention certain electricallycontrolled means are used, but these are without exception of a kindwhich require only little power, and for which the required power caneasily be produced locally, if necessary.

According to the present invention electrically coupled repeater devicesare used in the trans mitter and in the receiver. Such devices maycomprise threephase-singlephase wound rotating transformers or otherdevices in which any error in position between the transmitter deviceand the receiver device is indicated by a voltage at the outputterminals of one of the repeater devices. According to the inventionthis voltage is fed to a T- transformer and produces a controlled directcurrent voltage which actuates a relay controlling the pressure operatedmotor. Further details of the invention will be apparent from thefollowing description, taken in connection with the drawing in which thefigure is a diagrammatic representation of a system embodying thepresent invention.

In the figure a shaft I is coupled with the device II at thetransmitter, which may for instance comprise a telescope or the like,the angular movement of which is to be transmitted. On the shaft I0 ismounted a repeater l2. The shaft II] also carries a gear 13 the purposeof which will be further described.

The device at the receiver, which may for in stance comprise a militarypiece such as a gun or search-light to be controlled, is indicated at 2omains 20.

II. The piece I4 is controlled by means of a gear l5 carried on theshaft l5 of the piece l4 and meshing with a gear l6 mounted on a shaftll which is driven by the pressure actuated motor l8. On the shaft I!there is also mounted a repeater I9 which is electrically coupled to therepeater l2. In the embodiment shown the repeaters are assumed toconsist of a three-phase stator and a single-phase rotor. Thesinglephase winding of the repeater I9 is fed from mains withalternating current, preferably of a rather high frequency. There willbe induced in the single-phase rotor-part of the repeater I2 a voltagethe magnitude of which is a function of the angular position of therotor in question in relation to the stator. The single-phase currentthusincluced is fed by means of a line 2| to a T-coupled transformer 23,one winding of which is fed by means of a line 22 from the The twovoltages are algebraically added in the transformer 23 and the resultantis fed to a pair of opposed rectifiers 24, 25, working into loadresistors 26, 21 which are shunted for alternating current by means ofcondensers 28,

25 29. The resistors .26, 21 are connected in series.

One end of the resistors is grounded, whereas the other end is connectedwith the control grid of an amplifier tube 30 by a line containing afilter 3 i for filtering out any alternating current ripp e.

A battery 32111 the cathode lead of the tube 30 forms a self-bias. Inthe anode lead there are arranged in series a resistor 33 and aninductance coil 34. Finally the anode of the tube 30 is connected to thecontrol grid of another tube 35, the anode lead of which is connected tothe winding of a control relay 36 for the pressure control valve. Thisrelay controls a compressed air nozzle 31' to supply air either to theone side or the other side of a piston 39 which is movable in a cylinder38. The piston 39 is mechanically connected to a valve 40, which isarranged to open a pipe for the supply of fluid under pressure to themotor l8.

On the shaft of the pressure actuated motor I8 is mounted a gear 42cooperating with a gear 43, carried on the shaft of arepeater 44. Thisrepeater 44 is coupled to a repeater 45 on the transmitter side by meansof a three-phase line 46. Both of the repeaters 44 and 45 are fed withalternating current, preferably of a lowfrequency, from mains 41. Therepeaters 44 and 45 therefor will automatically follow each other. Theshaft of the repeater 45 is connected to a contact disc 48, carrying abrush 48' which engages contacts 49a or 48b on a second contact disc 48.A brush 48:: makes contact with the disc 48. This brush is connected bya line 48b to supply grid bias to the tube 80. Contacts 48a and 48b areconnected by lines 480 and 4911 to sources of positive and negativepotentials respectively. The contact arrangement is arranged in such away that the brush 4! takes three different positions, viz. a normalposition in which no contact is closed, and two outer positions in whicheither of the contacts 48a or 48b are closed to supply two difierentbiases to the control grid of the tube 38.

The arrangement functions in the following manner: Initially there isexactly 90 angular displacement between the rotors in the two repeatersl2 and [8. It should be noted that the repeater it obtains its singlephase voltage from the terminals 20. This voltage is transferred bytransformer action to the three-phasewinding of the repeater l9. Thereactually is no threephase current produced in this winding, but thethree winding parts will carry voltages which, when added algebraically,correspond to the single-phase voltage impressed from the terminals 20multiplied by a conversion ratio. These voltages are transferred overthe three conductors 5| to the repeater I2, and produce a field in therepeater l2 which fully corresponds to the field which is produced inthe repeater [8 by the voltage impressed at the terminals 20. If thesinglephase winding in the repeater I2 is perpendicular to the fielddirection no voltage is induced in thi single-phase winding, and both ofthe repeaters are than regarded as in corresponding positions.

The same voltage is impressed on both of the rectifiers 24 and 25 by theconductors 22, thus producing equal and opposite D. C. voltages acrossthe resistors 28 and 21. The, point 52 will therefore be at earthpotential.

If the transmitter I l is turned without a corresponding movement of thereceiver l4, the singlephase winding in the repeater l2 will no longerbe perpendicular to the direction of the field due to the three-phasewinding of the repeater l2. Consequently a voltage will be induced inthe transformer 23 which, for instance, is added to the voltage appliedto the rectifier 24 from the conductors 22 and subtracted from thevoltage applied to the rectifier 25 from the conductors 22 (or viceversa). In this case the direct current voltage drop across theresistance 28 is increased and the direct current voltage drop acrossthe resistance 21 is decreased by the same amount. The voltage at thepoint 52 will thus be displaced in a positive or in a negative directionfrom the ground potential, dependent upon the direction of movement ofthe single-phase winding of the reheater i2 from its normal position.The direct current voltage at the point 52 produces a pure directcurrent amplification in the electronic tubes 30 and 38 and energizesthe relay winding 38 to cause a corresponding displacement of the nozzle81. Air under pressure is impressed either above or below the piston 89in the cylinder 88 to actuate the valve 48 in a direction to cause themotor [8 to rotate the receiver l4, and also the repeater is in such away that the field of the three-phase winding in the repeater I2 isturned. The voltageacross the conductors 2| then becomes'zero and thear-- rangement comes to rest.

However, the receiver l4, the motor I: and the parts II, I8, l1, and I!may have a total mass which is so great that hunting develops. In orderof avoiding this hunting movement the resistance 23 and inductance coil34 are connected in the anode circuit of the tube II. It is known thathunting movement can be prevented by applying to the'allgnment motor aforce proportional to the sum of the magnitude of control movement andthe first derivative of the control movement. The voltage drop producedin the resistance 33 in the present case is a function of the controlmovement'and the voltage drop across the inductance coil 34 is afunction of the first derivative of the control movement. Consequentlythe movement of the motor l8 may be made fully free from hunting if theresistance 38 and the inductance 34 are made of the correct value. Thecorrect relation between these values will be dependent upon the masseswhich are put in movement by the motor 18, and it is thereforepreferable to make the resistance 33 adjustable so that the correctrelation between the resistance 38 and the inductance 34 may be obtainedbefore the system is put in use.

The movement of the motor II is transferred by means of the shaft l1 andthe gears 42, 43 to a second repeater 44. This is electrically connectedwith the repeater 45 on the transmitter side. However, as the load ofthe repeater 45 on the transmitter side is very small, viz. only thedisc 48, the magnetic force of the repeater is sufficient forcontrolling the disc 48 with the desired precision.

Hence it is suflicient to connect the singlephase windings in the tworepeaters to a source of alternating current 41 and to connect thethree-phase windings of both of the repeatersby means of a. three-phaseline 45. The repeater 45 then will follow the movement of the repeater44. The disc v-l8 is used for obtaining a follow-up signal, that is, togive a visual indication on the transmitter side that the movement ofthe transmitter II is followed by the receiver [4. It is also used forautomatic control. In the case of large movements of the transmitter Hcorresponding to morethan half a. turn of the repeaters l2 and IS, anerror in movement may be introduced between the transmitter II and thereceiver l4 with the single-phase winding of the repeater l2 extendingperpendicularly to. the field direction but displaced from its correctposition. However, this error in position will also be present betweenthe discs 48 and 49, and will close one of the two contracts 49a, 49b,dependent upon whether this error in position is positive or negative.The control grid of the electronic tube '30 is thus fed with a voltagewhich is either negative or positive in relation to ground. This voltageis isolated from ground and the resistances 28. 21 by means of the firstresistance in the filter arrangement 8|.

The result of this connection will be that the current through thewinding 38 becomes either stronger or weaker than the normal current andthe nozzle 3'! is shifted to introduce air either above or below thepiston 39 in the cylinder 38 until the motor l8 corrects the error inposition between the discs 48 and 45 and opens the contact 49a or 492;.The final line control of the receiver [4 then takes place in the abovementioned manner.

Of course the invention is not limited to the above embodiment butvarous modifications may be made therein without departing from thescope of the invention.

What is claimed:

1. A pressure actuated remote control system for causing a remotereceiver to follow the movement of a transmitter, comprisingelectrically coupled repeaters connected respectively to saidtransmitter and said receiver, means supplying an alternating energizingvoltage to one of said repeaters, a differential rectifier, meanscombining the output voltage of the other repeater and said alternatingvoltage to obtain a resultant voltage, means supplying said resultantvoltage to said rectifier to obtain therefrom a D. C. voltage having adirection and a value which is a function of the relative angulardisplacement of said repeaters, a servo-motor connected to. drive saidreceiver and the repeater connected thereto, an amplifier tube connectedto be energized by said D. C. voltage and to supply output energy forcontrolling the operation of said servo-motor,

and means associated with said amplifier tube to introduce voltage dropsto develop control forces proportional to the magnitude of the controlmovement and to the first derivative of the control movement.

2. A pressure actuated remote control system for causing a remotereceiver to follow the movement of a transmitter, comprisingelectrically coupled repeaters connected respectively to saidtransmitter and said receiver, means supplying an alternating energizingvoltage to one of said repeaters, a difierential rectifier, meanscombining the output voltage of the other repeater and said alternating'voltage toobtain a resultant voltage, means supplying said resultantvoltage to said rectifier to obtain therefrom a D. C. voltage having adirection and a value which is a function of the relative angulardisplacement 0L, said repeaters, a servo-motor connected to drive saidreceiver and the repeater connected thereto 35 and an amplifier tubeconnected to be energized by said D. C. voltage and to supply outputenergy for controlling the operation of said servomotor, said amplifiertube having an anode supply circuit and an inductance and a resistanceconnected in said anode circuit to introduce voltage drops to developcontrol forces proportional to the magnitude of the control movement andto the first derivative of the control movement, respectively.

3. A pressure actuated remote control system for causing/a remotereceiver to follow the movement of a transmitter, comprisingelectrically coupled repeaters connected respectively to saidtransmitter and said receiver, means supplying an-alternating energizingvoltage to one of said repeaters, ,a difierential rectifier, meanscombining the output voltage of the other repeater and said alternatingvoltage to obtain a resultant volt-,

age, means supplying said resultant voltage to said rectifier to obtaintherefrom a D. C. voltage having a direction and a value which is afunction of the relative angular displacement of said repeaters, aservo-motor connected to drive saidreceiver and the. repeater connectedthereto, a second pair of repeaters connected to indicate at thetransmitter the position of the receiver and means at the,transmitteractuated by the diiference in position between said last repeater andthe transmitter, to control said servo-motor independently of said firstcontrol, for causing said motor to correct said difference in position.

4. A pressure actuated remote control system for causing a remotereceiver to follow the movement of a transmitter, comprisingelectrically coupled repeaters connected respectively to saidtransmitter and said receiver, means supplying an alternating energizingvoltage to one of said repeaters, a diiferential rectifier, meanscombining the'output voltage of the other repeater and said alternatingvoltage to obtain a resultant voltage. means supplying said resultantvoltage to said rectifier to; obtain therefrom a D. .C. voltage havingadirection and a value ,which is a function of the relative angulardisplacement of said repeaters, a servo-motorconnected to drive saidreceiver and the repeater connected thereto, a second pair of repeatersconnected to indicate at the transmitter the position 0? the receiverand switch means at the transmitter actuated by a .diilference inposition between said last repeater and said transmitter to supply a D.C, voltage to said control means to cause actuation thereof to correctsaid difierence in position.

' RUNE HULTIN.

